(1) Field of the Invention
The present invention relates to a drinks preparation device comprising a brewing chamber having an outlet which is suited for housing loose coffee powder and for preparation of a drink by the use thereof.
(2) Description of Related Art
The prior art includes drinks preparation devices which make use of loose coffee powder or pre-portioned coffee or milk concentrate or milk powder portion units. Such portion units may be available in the form of aluminum or plastic capsules or in the form of paper pouches wherein the contents of the portion units is determined for the preparation of a normal amount of coffee, milk or milk foam for one cup of a coffee, milk or coffee-milk beverage.
Prior art commercial drinks preparation devices are designed having a brewing unit which includes only one single brewing chamber for using loose coffee powder and is equipped for the preparation of milk foam with a steam nozzle and optionally with a frothing-up aid.
Coffee preparation devices for the use of lose coffee powder are provided with brewing chambers in the shape of brewing pistons or integrated brewing chambers which are supplied with ground coffee powder from coffee grinders integrated in the preparation devices. The preparation of milk foam is effected in this connection by using hot steam and fresh milk. Milk foam preparation is effected either manually by means of the steam nozzle in a separate container filled with fresh milk, or automatically in that, in a special frothing device, milk is sucked in from an external container and is frothed by means of the steam streaming with high speed from the steam generator.
Commercial drinks preparation devices comprising one brewing unit which are designed for use of pre-portioned portion units for coffee or milk extract or milk powder, are equipped with only one housing chamber for such portion unit. In such a case, it is possible to insert into the same housing chamber alternately a pre-portioned coffee portion unit for drinks preparation or a pre-portioned milk or milk powder portion unit to use it for milk or milk foam preparation. In this case, the portion units are available in the form of aluminum or plastic capsules (EP 1 06 04 915 A1).
Suggested was also a drinks preparation device for the parallel use of pre-portioned portion units for coffee and milk powder where both a housing chamber for a coffee portion unit and a housing chamber for a milk powder portion unit have been provided.
In the case of the prior art drinks preparation devices which work with ground loose coffee powder and are equipped, for milk foam preparation, with a steam nozzle or automatic frothing devices, it is necessary for the preparation of a coffee-milk beverage to proceed in two subsequent steps in the coffee and the milk foam preparation. Since in such devices preferably the same heat exchanger is used for brewing water heating and for steam generation and for steam generation which requires higher temperatures than for brewing water preparation, this results in different heating and cooling times for the heat exchanger and hence in distinct time lags for each subsequent preparation.
In the same way, in preparation devices the brewing units of which are equipped with only one housing chamber both for housing coffee portion units for the preparation of coffee and for housing milk or milk powder portion units for the preparation of milk foam, wherein the milk foam is not generated from fresh milk by means of steam but rather from milk powder with water having the same temperature as for the coffee preparation, i.e. no time lags by heating or cooling processes of the heat exchanger are necessary, significantly retarded preparation processes will occur since in view of the use of the same brewing or housing chamber for coffee, milk or milk powder portion units, it is unavoidably necessary that each second mode of preparation has to be performed in a second operation which means that after one coffee preparation cycle, for instance, first the used-up coffee portion unit has to be removed from the brewing unit, subsequently the milk or milk powder portion unit has to be inserted into the brewing unit and, finally, after the preparation cycle, has to be disposed of.
While the suggested construction of a preparation device the brewing unit of which is equipped both with a housing chamber for coffee portion units and a housing chamber for one milk powder portion unit avoids the retardation by successive feeding and removing, it is exclusively designed for the use of two portion capsules.
The disadvantage of the preparation devices which operate with loose coffee powder is, therefore, to be seen in that for preparing milk foam the preparation device has to be equipped with a steam generation device, where for steam generation a higher temperature is required than for coffee preparation, which in the normal utilization of the same heat exchanger for the brewing water and for the steam generation leads to distinct retardations in the preparation of a coffee-milk beverage because of the heating-up or cooling-down phases of the heat exchanger.
The disadvantage of the preparation devices operating on the base of coffee portion units is to be seen in that distinct prolongations of the coffee-milk beverage preparations are experienced because of the successive feeding and removing steps and the coffee preparation is not based on freshly ground coffee powder.